Marine Expedition Crosses Over into … the Twilight Zone

Below:

Next story in Science

Just as TV producer Rod Serling took his audiences to "a fifth
dimension beyond that which is known to man … an area which we
call the twilight zone," the royal research ship James Cookhas
taken scientists to the North Atlantic to study the "twilight
zone" of the ocean — a region between 100 and 1000 meters (330 to
3,300 feet) below the sea surface, where the sunlight that
dapples the upper ocean reaches into the inky black depths.

The ship set sail from Glasgow, Scotland, on May 31, for the
Porcupine Abyssal Plain 350 miles (560 kilometers) southwest of
Ireland. During the two-week expedition, researchers will study
how life in the upper ocean influences the transport of carbon
from the atmosphere down to the deep ocean.

The oceans take up a third of the human-produced carbon in the
atmosphere, either by dissolving carbon dioxide or by marine
organisms consuming it. The ocean can store this carbon for
anywhere from days to thousands of years. [ Venturing
to the Ocean's Twilight Zone ]

The sunlit region near the ocean surface hosts an abundant
community of
phytoplankton and other tiny organisms, some of which
take up carbon dioxide to use in photosynthesis. When these
organisms die, their bodies and bodily wastes form carbon-rich
particles known as marine snow that filters down toward the ocean
floor. In the
twilight zone, some of this carbon is broken down and mixes
back up to the surface, while the rest sinks to the sea bottom
and is buried for centuries. The expedition is trying to figure
out how the structure and function of the biological communities
above the twilight zone affect how much carbon is being
transported to the deep ocean.

"The flux of carbon is important from the point of view of
mankind's production of carbon," said expedition leader Richard
Lampitt, a biogeochemist at the National Oceanography Centre in
Southampton, England. "We want to gain an understanding of what
is happening now and what is likely to happen in the future,
assuming mankind is incapable of cutting back on carbon
emissions," Lampitt told LiveScience.

The James Cook is based at the
Porcupine Abyssal Plain sustained observatory (PAP), an
instrument-laden stretch of open ocean at a depth of 3 miles (4.8
km) that has been gathering data about the marine environment for
more than 20 years.

Lampitt and his colleagues are collecting microscopic plants and
phytoplankton from the top ocean layer using water bottles, and
capturing zooplankton (which eat the phytoplankton) using nets
and a device called a video plankton recorder. Drifting sediment
traps called PELAGRA traps — much like rain gauges — onboard an
autonomous underwater vehicle are collecting marine snow
particles down to a depth of about 1,650 feet (500 m). Cameras on
these traps record the size and sinking rate of the particles. A
device called the Marine Snow Catcher is used to collect water
from the twilight zone that can be analyzed onboard the ship.

The marine snow sinks at a rate of roughly 100 m (330 feet) per
day. Measuring the rate at which particles sink may sound
trivial, but is extremely difficult because of the water
currents, Lampitt said.

The study site also has listening devices to capture whale
sounds. A pod of pilot whales has already been spotted spying on
the ship, the researchers reported on their blog.

The first week of the project has been successful, and the team
has another week to go. It will be months before the team has
results from the expedition, but the photographic technique they
developed for imaging marine snow particles has worked
astonishingly well, Lampitt said.